400 Pontiac rear main seal.

I actually have two questions: 1. Can the rear main seal be replaced with the motor in the car,it's in my 78 Trans AM. and # 2 I have a brown substance in my radiator after I drive the car and the radiator heats up anyone else see this in their car.It has an aluminum radiator and I'm not sure if I can flush it.Any help will be appreciated. Thanks.

jimus,I've heard you can, although I've never done it in the car. By the time you disconnect everything to lift to motor to get the clearence to drop the oil pan, IMO you might as well pull the motor. Is your brown substance oily in nature? you might possibly have a head gasket seeping oil into the water jacket, or it could just be way over due for a flush and coolant change. You should be able to flush the radiator regardless of whether it's aluminum or not.
Jim,

jimus08:I actually have two questions: 1. Can the rear main seal be replaced with the motor in the car,it's in my 78 Trans AM. and # 2 I have a brown substance in my radiator after I drive the car and the radiator heats up anyone else see this in their car.It has an aluminum radiator and I'm not sure if I can flush it.Any help will be appreciated. Thanks.

The seal can be replaced without pulling the motor, but it will be much easier to do with it out. Also, with it out, you can use one of the great new one piece BOP seals.

I repaired/replaced the rope seal in my '69 GTO, without pulling the motor. But it wasn't easy. Of course, you must remove the oil pan. Then remove the cap. Next, you make a tool from a piece of rod the correct size. Or I suppose you could use a large round punch and grind the end to the correct size and shape.

What you need is a tool to punch or pack the ends of the rope seal down into the seal groove. Then you work the end of one of the new ropes down into the groove as far as you can get it to go. When it won't go any farther, use your razor blade or exacto knife and trim the rope off even with the block.

Then repeat this process on the other end of the rope. When you've done this, replace the old rope that is in the cap, with the new rope and pack it down into the groove with a section of pipe or something that is nearly 3 inches in diameter. Keep tapping on the pipe with a hammer til the rope is packed down nicely into the groove. Then trim the ends of the rope even with the cap, and torque the cap back on.

Hey, it ain't easy, but it can be done. I'm a witness. I raced my GTO for 2 seasons after this fix, and it didn't leak. But I still recommend pulling the motor and installing the one piece BOP seal.

SEAL - yes the rear seal can be replaced in the car. very common. you need the two piece rubber seal. if you have a rope seal you need to drive the pin out of the seal area in the main cap. easy deal. you also need a seal remover tool if you have a rope seal. might be seven bucks for the tool.

RAD WATER - It is most likely rust from your engine. inbstall a gano filter. if you get chunks of rust in your rad you can never ever get them all out of an aluminum rad.